Researches on the comparative dynamic stereochemistry of electron impact induced eliminations and related thermal reactions such as, for example, the pyrolysis of acetates, are proposed as the route to bridge the structural information gap between accessible phase molecules and rapidly decomposing gaseous ions. The sought after structural properties of species reacting unimolecularly in high vacumn form the foundation for not only all advances in the analytical potential of mass spectrometry but as well for the growing use of gaseous ion molecule reactions as one of the means of isolating and understanding the role of solvent in condensed phase. In addition to these goals, this work has also lead to expanded use of mass spectrometry as a tool to study stereoisomers, especially deuterated molecules of interest in biochemical and organic chemical mechanistic work. Further, our efforts involve the preparation of molecules and measurements which will act to elucidate the mechanism of reactions for the activation of remote methylene groups by alkoxy radicals. Indeed studies under this grant have led to the development of a new reaction for forming remote carbon-carbon double bonds by metal ion catalyzed decomposition of hydroperoxides.